The Updating an Existing DITA CMS v4.2 Deployment (Update Guide) explains how to bring your deployment up to date to a more current build release. The build number of the software increases (for example, from 4.2.33 to 4.2.34) to introduce bug fixes, which may require small updates to the DITA CMS components.
To update your deployment, you must update each component in your deployment with the newer version of the software and then you may also need to make some changes to some components' configuration files to support the changes made in the software.
If you are upgrading to a minor version (for example, from version 4.1 to 4.2) or to a major version (for example, from version 4.2 to 5.0), you must follow the instructions in Upgrading the DITA CMS to 4.2 instead. An upgrade may require may require upgrades to the underlying framework, configuration changes, or upgrades to the DITA CMS components which are provided in that document.